As a fluid mixed with a solid component and a liquid component, for example, river water, sea water, blood, milky liquid or the like is included. Solid components of sand, bacteria, blood cell, emulsion or the like included in the fluids are present at inside of the fluids in a state of precipitation, dispersion or the like. That is, the solid component is present as a solid without being dissolved in the liquid component.
An explanation will be given of a method, a device of separating the fluid mixed with the solid component and the liquid component into respective components of, for example, a blood cell/blood plasma separating device or the like as follows.
Normally, blood sampled for inspection is sampled in a whole blood state constituted by blood plasma which is a liquid component, a blood cell which is a solid component and other component. However, there is frequently a case in which a component necessary for inspecting blood is only a blood cell portion, or conversely, a blood plasma portion. For example, in order to inspect a blood sugar level in blood, blood sugar dissolved in a blood plasma component is measured. In order to inspect DNA, DNA is sampled from leukocyte cell which is a kind of blood cell.
Therefore, in order to inspect blood, prior to inspection, there is used a step of separating respective components present in blood. A method of separating a component of a background art is generally a method of putting sampled blood in a whole blood state into a test tube to be mounted to a centrifugal separator and applying a predetermined centrifugal force to thereby separate blood into a blood plasma component and a blood cell component.
In this way, the blood in the whole blood state at inside of the test tube is applied with the centrifugal force by the centrifugal separator. Thereby, respective components undergo centrifugal forces in accordance therewith to be separated into the respective components by differences in masses. Thereafter, by extracting a supernatant fluid, the blood plasma component is taken out. The blood cell component or the like is taken out from a precipitate. Thereafter, the respective components are inspected by being subjected to predetermined measurement in an inspecting step.
In separating the components by the centrifugal separator, in view of operation of the centrifugal separator, a constant amount or more of a fluid is needed and the separation is not suitable so much when a sample amount is small.
As a method of separating a sample of a small amount of a liquid, there is also a method of using a filter. The method is a method disclosed by Yong-Kyu Yoon and other, which utilizes a porous characteristic of the filter. For example, by filtering blood cell having a predetermined size or more, the blood plasma component is provided, conversely, blood cell is taken out. According to the method, a hole size, number or the like of the filter have an influence on a separating characteristic. Therefore, it is required to design an optimum filter by which component is to be separated. It is also required to accurately reproduce the hole size, number or the like of the filter. For example, a method of accurately reproducing hole size, number or the like of the filter is a method of providing a filter in a mesh-like shape by exposing a photosensitive resist three-dimensionally. The method is disclosed in, for example, Yong-Kyu Yoon “Integrated vertical screen microfilter system using inclined SU-8 structure.” MEMS2003, Kyoto, PP. 227-230 issued by IEEE.
Also a device for carrying out manipulation of particles suspended in a fluid is utilized. The component separating method, for example, is disclosed in Japanese Translation of PCT Publication No. 2001-525722 (hereinafter, referred to as Patent Reference 1). A component separating apparatus disclosed in Patent Reference 1 includes a duct, an ultrasonic transducer, and a reflector. The duct is provided for making the fluid suspended with particles flow. The ultrasonic transducer is arranged on one side of the duct and the reflector is arranged on an opposed side of the duct. An acoustic standing wave vibration (hereinafter, referred to as standing wave) traversing the duct in a width direction is generated by the duct, the ultrasonic transducer and the reflector. By the standing wave, particles suspended in the fluid are agglomerated to constitute one or more of plane bands in parallel with a longitudinal axis of the duct. Thereby, particles, which are a solid component, and a liquid component are separated.
According to the constitution, the ultrasonic transducer is brought into direct contact with an inner portion of the duct and therefore, there is a case in which the ultrasonic transducer is contaminated by a fluid flowing at inside of the duct. Further, the ultrasonic transducer constitutes a part of the duct. Thereby, there is not a freedom of designing the ultrasonic transducer, further, it is difficult to accurately position the duct and the ultrasonic transducer.